Question

find the mean and median of first 12 odd composite number.

Answer 1

$$\begin{gathered} \mathrm{The}\mathrm{first}12\mathrm{odd}\mathrm{composite}\mathrm{numbers}: \\ 9,15,21,25,27,33,35,39,45,49,51\mathrm{and}55. \\ \mathrm{Now},\mathrm{sum}\mathrm{of}\mathrm{numbers}=9+15+21+25+27+33+35+39+45+49+51+55=404 \\ \mathrm{Now},\mathrm{mean}=\frac{\mathrm{sum}\mathrm{of}12\mathrm{observations}}{12}=\frac{404}{12}\approx 33.67 \\ \mathrm{Now},\mathrm{number}\mathrm{of}\mathrm{oservations}=\mathrm{n}=12\left(\mathrm{even}\right) \\ \mathrm{Median}=\frac{\mathrm{value}\mathrm{of}{\left({\displaystyle \frac{\mathrm{n}}{2}}\right)}^{\mathrm{th}}\mathrm{observation}+\mathrm{value}\mathrm{of}{\left({\displaystyle \frac{\mathrm{n}}{2}}+1\right)}^{\mathrm{th}}\mathrm{observation}}{2} \\ =\frac{\mathrm{value}\mathrm{of}{6}^{\mathrm{th}}\mathrm{observation}+\mathrm{value}\mathrm{of}{7}^{\mathrm{th}}\mathrm{observation}}{2} \\ =\frac{33+35}{2} \\ =\frac{68}{2} \\ =34 \end{gathered}$$